Semirigid brake shoe



Mai 29, 1934. w, o w Re 19,188

SEMIRIGID BRAKE snos Original Filed June 4, 1928 2 Sheets-Sheet l /-/AMI y 1934- w. F. OLIVER Re. 19,188

SEIIRIGID BRAKE SHOE Originil Filed June4. 1928 2 Sheets-Sheet 2 do a 11 .g .-v :12 33 Reissued May 29, 1934 UNITED STATES PATENT OFFICESEMIRIGID BRAKE SHOE Qrlglnal No. 1,832,135, dated November 17,

282,661, June 4, 1928. Application Serial No.

for reissue May 11, 1933, Serial No. 670,597

'18 Claims. (Cl. 188-78) My invention relates to improvements insemirigid brake shoes.

The invention will be explained as embodied in that type of brake shoeemployed in the brake assembly of an internal expanding brake mechanism.

An object of the invention is to provide an improved semirigid brakeshoe.

A further object is to provide a semirigid brake 1o shoe in which thatpart bearingthe brake lining is forced into unii'orm engagement with thebrake drum by means independent of the'brake shoe applying mechanism andthereupon set to normally maintain complete and uniform engagement oithe shoe with the drum throughout the length of its entire brake liningsurface.

Another object is to provide a semirigid brake shoe in which a part ofthe adjusting mechanism performs the two-fold function of causing go theflexible part of the brake shoe to conform with the contour oi the brakedrum during adjustment and which also serves as a limiting stop for theshoes when released from engagement with the drum as during use. I

Another object is to provide a semirigid brake shoe of) the articulatedtype, wherein under normal conditions the heel portion of the shoe isrendered substantially rigid and the toe portion relatively flexible andthe entire work-engaging portion of the shoe subject to flexibilityduring adjustment. Where the expression flexible brake shoe is'usedherein this expression is to be interpreted as meaning a brake shoewhich will flex very slightly under operating pressures.

A further object is to provide a semirigid brake shoe of the articulatedtype having a rigid supporting part and a relatively flexiblework-engaging part associated with one another in such a manner as topermit relative flexibility of the toe oi the shoe, yet retain rigidityat the heel portion.

A further object is to provide asemirigid brake shoe which is extremelysimple in construction, which may be readily assembled and disassembledand in which the relatively flexible part may be removed withoutdisengaging the shoe from its pivotal mounting in the brake assembly.

Other objects and advantages will be more particularly pointed out inthe following specification and appended claims. p In the invention, asillustrated in the accompanying drawings forming a part of this applica-.tion.

\ Figure 1 is a side elevation, a part thereof in section 01 an internalexpanding brake assembly showing the semirigid shoe in use;

Figure 2 is a view along the line 22 of Figure 1; I I v Figure 3 is anenlarged sectional view along the line 3-3 of Figure 1;' V

Figure 4 is an enlarged sectional view along the line 4-4 of Figure 1;and

Figure 5 is a diagrammatic view illustrating the manner in which thewheel cylinders of the hydraulicbrake system are actuated.

In general, the semirigid brake shoe consists in substantially rigidtwo-part supporting memher A having a bearing portion B for pivotalengagement with a mounting pin C, a relatively flexible member Dsupporting a brake lining E pivotally secured at F to support member Aand retained against movement thereto at the heel part by an adjustmentand locking bolt G.

The supporting member A consists (see Fig. 2) of a complementary pair ofmalleable metal plates 5 heavily reinforced by rib portions 6 extendinglaterally from the peripheral portions of the plates. Registeringbearing portions B are formed in the plates toreceive the brake shoe 30mounting pin C. In a complete brake assembly there are two such pinsrigidly secured to the rear cover or dust plate 8 of the assembly.

Registering bores 9 are provided in the upper ends of plates 5 forreceiving the bolt F, which 35 extends through an opening 10 formed inthe web portion 11 of the relatively flexible member D. Thus the memberD is pivotally supported upon the support member A, which in turn ispivotally supported upon mounting pin C. Bolt F has a nut 12 and lockwasher 13 by means of which plates 5 are drawn toward one another andtightly clamp web 11 thereto. Small metal washers 14 are disposed onbolt F, one on each side of web 11, so that the web does not contactwith plates 5 at any point throughout its disposition between theplates.

Means for securely locking the heel portion 15 of'flexible member D tothe rigid member A and for permitting adjustment of member D upon itspivotal support F, consists in bolt G which extends through alignedopenings 1'7 provided in plates 5 and through an elongated slot 18 inthe web portion 11 of member D. The longitudinal axis of slot 18 issubstantially concentric with belt F. As in the case 01' bolt F, a pairof small washers 19 are disposed one on each side of web 11 upon bolt G.A nut 20 and lock washer 21 are provided for bolt G, so that web noIlulutmayliesecui'elybtiumlbetweenplaterlliat The relatively flexiblemember D has an integral flange at its peripheral edge forsupportingabrakeliningEandthereforeliesin a plane concentric with thebrake drum 26 of r the wheel assembly.

The inner end of bolt F carries a concave disc 30 secured to an inwardlyextending pillar 31 which cooperates with an adjustable cam 32 carriedby threaded shaft 33 mounted and extending through cover 8 for limitinglateral movement of the shoe and for limiting the retractile movement ofthe shoe away from brake drum 26. A lock nut 34 and lock washer 35 areprovided for shaft 33 to set the shaft against movement when adjusted.

In the drawings I have illustrated a hydraulic actuating means for thebrake shoes, though the shoes herein described may be actuated withequal success by any one of the several wellknown brake shoe actuatingsystems.

With reference to Figures 1 and 5, a wheel cylinder 35 is mounted withinbrake drum'26 and has a pair of opposed pistons 36 therein,-. each ofwhich engage at 37 with integral tongues 38 formed in members D. Fluidunder pressure is admitted to cylinder 35 through a passage 39communicating with fluid ducts 40. The fluid ducts 40 are connected witha master cylinder 41 having a master piston 42 which is actuated bymanual manipulation of a foot pedal 43. The reserve supply of fluid ismaintained in a reservoir 44 communicating at 45 with a master cylinder41 at such times as when the piston 42 is in its full retractileposition.

In operation, my improved semirigid brake shoe is amusted to conformitywith the brake drum by flrst releasing nut 20 so that the flexiblemember D of the shoe is free to pivot upon bolt F. At this time andduring the entire adjustment of the brake shoe, fluid pressure in thewheel cylinder 35 is released.

Nut 34 is next released andthe shaft 33 rotated with a wrench or specialtool provided for that se to causethe cam 32 to turn therewith and forcebolt 1'' toward the brake drum 26. This causes the flexible part D ofthe shoe to be forced into conformity with the curvature of the brakedrum, the application of force being at the midpoint of the flexiblepart. During this operation web 11 will shift upon its pivotal supportbolt F with respect to the rigid supporting member A which. is possibleby virtue of the elongated slot 18 formed in the web through which boltG extends. While the parts are thus positioned nut 20 is turned downtightly so as to draw the two malleable plates 5 toward one another andsecurely bind and lock the inner or heel end of the flexible part D toand against movement with respect to rigid supporting memher A at thatportion surrounding bolt G.

The adjusting'cam 32 is then moved in a counterclockwise direction(Fig. 1) until the clearance has been established between the brake drum26 and the surface of the brake lining E whereupon the nut 34 istightened so as to maintain the adjusting cam 32 in proper position toestablish the desired clearance between shoe and drum.

. In use, the heel part, i. e., that part of the shoe between bolt F andthat end adjacent to the pivotal shoe mounting C, presents asubstantially rigid brake drum engaging element, whereas that part ofthe shoe between bolt 1' and the tongues aa is relatively flexible. Thiscondition assures proper engagement of the shoe with the drum bypermitting somewhat greater application of pressure to the drum by theshoe at its toe or forward end, to cause the building up of a wrappingeiIect between drum and shoe in that shoe having its toe pointing in adirection opposite to the direction of the rotation of the drum.

The anchoring of the parts D to the rigid support A does not destroy therelatively flexible properties of the parts D because there is a spacebetween the components 5 of the rigid support A and the web 11 of theparts D except for that area immediately surrounding bolts F and G.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. In a vehicle wheel brake, a brake drum, a pivotally mounted rigidmember, a relatively flexible brakelining support pivoted intermediateits length to the free end of the rigid member, a cam for forcing theflexible support into close engagement with the brake drum, and meansfor securing the flexible support to the rigid member at a pointadjacent to the inner end of the flexible member whereby the innermostpart of the flexible member is rendered relatively rigid and the outerend mayremain relativelyflexible.

2. In a vehicle wheelbrake, a brake drum, a pivotally mounted rigidmember, a relatively flexible brake lining support pivoted intermediateits length to the free end of the rigid member, a cam for forcing theflexible support into close engagement with the brake drum, and meansfor securing the flexible support to the rigid member at a pointadjacent to the inner end of the flexible member whereby the innermostpart of the flexible member is rendered relatively rigid and the outerend may remain relatively flexible, said cam further serving as a stopto limit the movementof the flexible support away from the drum.

3. In a vehicle wheel brake, a brake drum, a mounting pin, a rigid platepivotally supported upon the mounting pin, a relatively flexible brakelining support pivotally moimted at a point intermediate its length tothe free end of the plate a cam for exerting outward radial pressure tothe flexible support at its point of connection with the plate to forcethe support into conformity with the curvature of the 'drum, and meansfor looking the inner end of the flexible support against movement withrespect to the plate while the flexible support is so forced against thedrum.

4. In a vehicle wheel brake, a semirigid brake shoe comprising a rigidmember forming the heel portion of the shoe, a relatively flexible brakelining support, in circumferential alignment with the rigid member andoverlappln8 the rigid member, a pivotal connection between the outer endof the rigid member and the adjacent part of the flexible support, andadjustable means for locking the inner end of the flexible support tothe adjacent part of the rigid member, whereby the heel portion of theflexible support is relatively unyielding and the remaining portion isrelatively flexible. V

.5. In a vehiclewheel brake, a semirigid brake shoe comprising a rigidmember forming the heel portion of the shoe, a relatively flexible brakelining support, in circumferential alignment with the rigid member andoverlappin the rigid member, 'a pivotal connection between the outer endof the rigid member and the adjacent part of the flexible support, andadjustable means for locking the inner end of the flexible support tothe adiaflexible support centpart oi the rigid member, that portion ofthe lying between the said pivotal connection and the said adiustablemeans being free of contact with the flexible support whereby the heelportion of the flexible support is relatively unyielding and theremaining portion is relatively flexible. v

6. In a vehicle brake, a brake drum, a relatively flexible brake liningsupport, operating means for applying pressure adjacent one end oftheflexible support to cause the support toadjust itself to the curvatureof the brake drum, rigid means for 1 support remote from said operatingmeans in adjusted position, and means associated with said rigid meansfor pivotally mounting the flexible support within the drum. 7. A brakeshoe having an anchor link pivoted near one end, a pivotal connectionbetween said shoe and said link, and other means spaced from saidpivotal means and passing through the shoe and said link and holding thelink in difierent angular positions.

8. A brake shoe' having an anchor link pivoted near one end, meansconnecting said shoe and said link, and a second means spaced from saidfirstnamed means and passing through the shoe and said link andi'rictionally clamping the link in different angular positions.

9. A brake shoe having an anchor linkarranged along its side near oneend of the shoe and en-. gageable with an anchor at said end of theshoe, a pivot connecting the link to the shoe at the end of the linkopposite the anchor, and a fastening between the pivot and anchor endfor holding the link in diflerent angular positions.

.10. A brake shoe having a link arranged along its side near one endoithe shoe, a pivot connecting the link to the shoe at the end of the linkopposite the end of the shoe,- and a fastening between the pivot andshoe end for holding the link in difl'erent angular positions.

11. A'brake shoe having an anchor link arranged along its side near oneend of the shoe and engageable with an anchor at said end of the shoe, apivot connecting the link to the shoe, and a fastening passing throughthe link and the ocking only that portion of the flexible shoeandholding the link in diflerent angular positions.

12. A brake shoe having a link arranged along its side near one end ofthe shoe, a pivot connecting the link to the shoe, and a fasteningpassing through the link and the shoe and holding the link indifl'eren't angular positio 13. A brake shoe having an anchor linkarranged along its' side near one end of the shoe and engageable with ananchor at said end of the shoe, a pivot connecting the link to the shoe,and a friction clamp bolt passing through the link and the shoe andholding the link in different angular positions. I

14. A brake shoe having a link arranged along its side near one end ofthe shoe, a'pivot connecting the link to the shoe, and a friction clampbolt, passing through the link and the shoe and holding the linkindiflerent angular positions.

15. A brake shoe having a pivot and a link mounted on the pivot andhaving an enlarged opening in the shoe some distance from the pivot,together with a clamp bolt passing through said opening and adjustabiysecuring the link to the shoe.

16. A brake shoe having a pivot and a link mounted on the pivot andhaving an-enlarged opening inthe link some distance from the pivot,together with a clamp bolt passing through said opening and adjustablysecuring the link to the shoe.

17. A brake, comprising a brake shoe, an anchor, a short link pivoted-atone end of said brake shoe and adapted to engage said anchor,

and means spaced from the pivotal connection between said link and saidshoe and providing said shoe. WALLACE F. OLIVER.

